This invention relates generally to biosynthetic processes and, more specifically to organisms having enhanced carbon fixation capabilities.
1,3-butanediol (1,3-BDO) is a four carbon diol traditionally produced from acetylene via its hydration. The resulting acetaldehyde is then converted to 3-hydroxybutyraldehdye which is subsequently reduced to form 1,3-BDO. More recently, acetylene has been replaced by the less expensive ethylene as a source of acetaldehyde. 1,3-BDO is commonly used as an organic solvent for food flavoring agents. It is also used as a co-monomer for polyurethane and polyester resins and is widely employed as a hypoglycemic agent. Optically active 1,3-BDO is a useful starting material for the synthesis of biologically active compounds and liquid crystals. Another use of 1,3-butanediol is that its dehydration affords 1,3-butadiene (Ichikawa et al. Journal of Molecular Catalysis A-Chemical 256:106-112 (2006); Ichikawa et al. Journal of Molecular Catalysis A-Chemical 231:181-189 (2005), which is useful in the manufacture synthetic rubbers (e.g., tires), latex, and resins. The reliance on petroleum based feedstocks for either acetylene or ethylene warrants the development of a renewable feedstock based route to 1,3-butanediol and to butadiene.
Isopropanol (IPA) is a colorless, flammable liquid that mixes completely with most solvents, including water. The largest use for IPA is as a solvent, including its well known yet small use as “rubbing alcohol,” which is a mixture of IPA and water. As a solvent, IPA is found in many everyday products such as paints, lacquers, thinners, inks, adhesives, general-purpose cleaners, disinfectants, cosmetics, toiletries, de-icers, and pharmaceuticals. Low-grade IPA is also used in motor oils. IPA is also used as a chemical intermediate for the production of isopropylamines (Ag products), isopropylethers, and isopropyl esters. Isopropanol is manufactured by two petrochemical routes. The predominant process entails the hydration of propylene either with or without sulfuric acid catalysis. Secondarily, IPA is produced via hydrogenation of acetone, which is a by-product formed in the production of phenol and propylene oxide.
4-hydroxybutanoic acid (4-hydroxybutanoate, 4-hydroxybutyrate, 4-HB) is a 4-carbon carboxylic acid that is used as a building block for various commodity and specialty chemicals. In particular, 4-HB can serve as an entry point into the 1,4-butanediol family of chemicals, which includes solvents, resins, polymer precursors, and specialty chemicals.
1,4-butanediol (BDO) is a valuable chemical for the production of high performance polymers, solvents, and fine chemicals. It is the basis for producing other high value chemicals such as tetrahydrofuran (THF) and gamma-butyrolactone (GBL). The value chain is comprised of three main segments including: (1) polymers, (2) THF derivatives, and (3) GBL derivatives. In the case of polymers, BDO is a comonomer for polybutylene terephthalate (PBT) production. PBT is a medium performance engineering thermoplastic used in automotive, electrical, water systems, and small appliance applications. Conversion to THF, and subsequently to polytetramethylene ether glycol (PTMEG), provides an intermediate used to manufacture spandex products such as LYCRA® fibers. PTMEG is also combined with BDO in the production of specialty polyester ethers (COPE). COPEs are high modulus elastomers with excellent mechanical properties and oil/environmental resistance, allowing them to operate at high and low temperature extremes. PTMEG and BDO also make thermoplastic polyurethanes processed on standard thermoplastic extrusion, calendaring, and molding equipment, and are characterized by their outstanding toughness and abrasion resistance. The GBL produced from BDO provides the feedstock for making pyrrolidones, as well as serving the agrochemical market. The pyrrolidones are used as high performance solvents for extraction processes of increasing use, including for example, in the electronics industry and in pharmaceutical production.
BDO is produced by two main petrochemical routes with a few additional routes also in commercial operation. One route involves reacting acetylene with formaldehyde, followed by hydrogenation. More recently BDO processes involving butane or butadiene oxidation to maleic anhydride, followed by hydrogenation have been introduced. BDO is used almost exclusively as an intermediate to synthesize other chemicals and polymers.
Thus, there exists a need for the development of methods for effectively producing commercial quantities of compounds such as 1,4-butanediol, 4-hydroxybutyrate, 1,3-butanediol, or isopropanol. The present invention satisfies this need and provides related advantages as well. Additional product molecules that can be produced by the teachings of this invention include but are not limited to ethanol, butanol, isobutanol, isopropanol, succinic acid, fumaric acid, malic acid, 3-hydroxypropionic acid, lactic acid, adipic acid, 6-aminocaproic acid, hexamethylenediamine, caprolactam, 3-hydoxyisobutyric acid, 2-hydroxyisobutyric acid, methacrylic acid, acrylic acid, 1,3-propanediol, glycerol, and long chain hydrocarbons, alcohols, acids, and esters.